There are multiple conditions for the ABS light to illuminate, with different causes and solutions for each condition, as detailed below: Condition 1: ABS warning light stays on constantly (most common). Cause 1: The ABS wheel speed sensor's sensing area is covered by dirt, mud, or other contaminants, affecting its ability to detect the corresponding wheel speed signal. This prevents the ABS control unit from determining the vehicle speed and wheel slip rate, thus failing to issue appropriate commands to regulate braking. Solution: Clean the contaminants from the wheel speed sensor and adjust the gap between the sensor and the tone ring to restore normal function. Cause 2: Poor signal transmission due to loose connections in the system wiring or poor contact in the ABS relay, leading to system malfunction. Solution: Inspect wiring connections and reconnect any loose parts. Condition 2: ABS warning light illuminates intermittently and turns off when accelerating. Cause: When multiple electrical devices are in use, the battery voltage drops below 10.5V. As engine speed increases and voltage rises, the ABS indicator turns off. This may also occur due to insufficient power supply voltage to the ABS system, such as poor terminal contact or grounding issues. Solution: Check the battery's specific gravity; inspect the charging system; examine the power supply (e.g., voltage relay or poor power contact). Condition 3: ABS warning light stays on after engine start and only turns off when the engine is turned off (IGFF). Cause: Poor grounding contact in the ABS hydraulic valve body; poor contact in the ABS hydraulic valve body wiring connector; ABS control unit malfunction. Solution: Loosen and retighten the hydraulic valve body grounding screw, cleaning the contact surface if necessary; check if the connector gap has widened; replace the ABS or ABS/ASR control unit. Condition 4: ABS warning light illuminates during high-speed driving. Cause: During high-speed driving, the ABS control unit detects a significant discrepancy between rear and front wheel speed signals; incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's tire and wheel rim specifications, as indicated on the fuel cap label. Condition 5: ABS warning light illuminates intermittently. Cause: Improper adjustment of the brake light switch; poor internal contact in the brake light. Solution: With the engine running, press the brake pedal and use a finger to push the brake switch linkage all the way down, then release the brake pedal to complete self-positioning; replace the brake light switch if necessary. If the ABS warning light is illuminated, it is advisable not to continue driving, as this indicates a malfunction in the vehicle's anti-lock braking system. During emergency braking, if the wheels lock up, the vehicle may skid uncontrollably, making it difficult for the driver to slow down or adjust the vehicle's trajectory, posing significant safety risks.
